GOP Hopefuls Take Shots at Trump Ahead of Debate

This Wednesday's Republican debate could turn into a rumble and the target is front-runner Donald Trump.

Trump's already taking heavy fire from his rivals as they try to break out of the pack and take down the outspoken billionaire.

Over the weekend, former Florida Gov. Jeb Bush, former Hewlett Packard CEO Carly Fiorina, and Sen. Rand Paul, R-Ky., took shots at Trump, who's grabbed the spotlight and won't let go.

Last week, retired neurosurgeon Ben Carson questioned Trump's faith, but later apologized.

Trump struck back, suggesting Carson has low energy, prompting the following response from Carson on ABC's "This Week."

"It doesn't bother me because I recognize that I have plenty of energy," he said. "You know, operating on people for 10, 12, sometimes for greater than 20 hours at a time, making critical decisions after many hours of intense work, having...unexpected situations come up."

Republican National Committee Chairman Reince Preibus said the attacks on Trump are about more than message. He told CNN some candidates will soon start running out of money and have to drop out.

Meanwhile, Wisconsin Gov. Scott Walker is highlighting his success in defeating the labor unions.

Today, he's calling for sweeping restrictions on organized labor, including doing away with unions for federal employees.